Abstract:

Modified Gompertz (SGompertz) and logistic (Slogistic) models were selected as the primary growth models to fit
the growth curves of Staphylococcus aureus in roast duck at various storage temperatures (10, 15, 25, 30 and 37 ℃). Using
the obtained specific growth rate (μmax) and lag time (λ), square root model and quadratic polynomial model were selected to
fit the secondary growth models of Staphylococcus aureus in roast duck. The results showed that the SGompertz model could
well describe the growth of Staphylococcus aureus at different temperatures, and therefore μmax and λ values obtained from it
were used to establish the secondary growth models. It was found that for the square root and quadratic polynomial models
based on μmax, R2 values were 0.942 3 and 0.947 1; Bf were 1.02 and 0.93; Af were 1.18 and 1.37, respectively, suggesting that
the square root model could be employed to predict the growth of Staphylococcus aureus in roast duck. For the square root
and quadratic polynomial models describing λ, R2 were 0.953 3 and 0.987 1; Bf were 0.99 and 1.00; Af were 1.11 and 1.06,
respectively, suggesting that the quadratic polynomial model could be employed to predict λ. This study can provide basic
information for quantitative microbial risk assessment of roast duck and other ready-to-eat cooked meat products.

Key words: Staphylococcus aureus, roast duck, primary growth model, secondary growth model